Coupled reservoir/wormholes model for cold heavy oil production wells

Cold heavy oil production (CHOP) is a non-thermal process in which sands are aggressively produced to obtain a higher oil production rate. It is believed that wormholes are generated during this process and that the wormholes provide the main conduits for fluid flow. A semi-analytical model coupling the reservoir/wormholes flow has been developed to analyze the performance of CHOP wells. The diffusivity equation in the model is solved by source functions, which has been widely practiced in solving the unsteady reservoir flow problems to analyze transient pressure behaviors of horizontal and multilateral wells. This model is also quite flexible to incorporate any wormhole hydraulic model; moreover, the model can be used under a variety of reservoir boundary conditions, such as closed systems, constant pressure systems, etc.In this paper, the effects of wormhole patterns, wormhole scales, wormhole diameters, wormhole branching, boundary conditions and pressure drop along the wormhole on the performance of CHOP wells have been analyzed extensively. The model not only provides a powerful tool to understand the effects of wormholes, but also offers a way to interpret well testing data and to analyze production rate declines of CHOP wells.